This invention relates to an electrical battery charging system, and more particularly to a controlled electrical battery charging system.
Electrical storage battery charging systems are well known in the art, as illustrated in the following U.S. patents:
______________________________________ 3,382,425 Legatti May 7, 1968 3,766,463 Ruben Oct. 16, 1973 3,854,082 Nasby et al Dec. 10, 1974 3,911,350 Swope Oct. 7, 1975 3,925,714 Sherman, Jr. Dec. 9, 1975 3,969,665 Rowas July 13, 1976 4,006,397 Catotti et al Feb. 1, 1977 4,019,111 Bennefeld Apr. 19, 1977 4,031,451 Gordon June 21, 1977 4,131,841 Bennefeld Dec. 26, 1978 4,163,934 Lawn Aug. 7, 1979 ______________________________________
All of the above patents, except the Swope patent 3,911,350, disclose battery chargers including a rectifier circuit incorporating SCR's for controlling the charging current.
The patents to Legatti, Ruben, Nasby et al, Rowas, Gordon and Lawn disclose SCR rectifier circuits in a battery charger which are triggered by a unijunction transistor.
The Ruben and Gordon patents also disclose a unijunction transistor with an RC timer circuit coupled to a control transistor.
In the Legatti patent, there is a DC voltage control circuit and a DC current control circuit for transmitting signals to the control transistor 66 in order to activate the unijunction transistor 46 and trigger the SCR's 10 and 12.
The Ruben patent discloses a voltage control circuit including the transistors Q5 and Q6 and a potentiometer R13.
The Nasby et al patent discloses a voltage control circuit and a current control circuit connected to an AND circuit 28 for activating the SCR control circuit 30.
The Swope patent 3,911,350 discloses a number of battery charging circuits incorporating a temperature sensor for sensing the temperature of the transformer in order to control the charging current.
The battery charging circuit of the Rowas patent 3,969,665 incorporates a thermistor 29 for sensing the temperature of the battery.
Catotti et al discloses a voltage control circuit and a temperature control circuit each of which is adapted to transmit excessive signals to an OR logic circuitry for triggering the SCR.
The Bennefeld battery charger includes a system for automatically changing from a current-controlled mode to a voltage-controlled mode. The integrated circuit chip 118 is used as a voltage regulator.
The Gordon patent 4,031,451 is an improvement over the Ruben battery charger and includes a current limiting circuit and an overshoot circuit for transmitting excessive or error signals to the unijunction transistor Q1 for triggering the SCR's in the rectifier circuit.
The U.S. patents to Ruben, Nasby et al, Catotti et al, both Bennefeld patents and the Gordon patent disclose battery charging circuits in which the system is not completely turned off after the battery is fully charged. These battery charging circuits include low current or trickle current after the battery has been substantially fully charged, primarily to maintain the charge on the battery.
None of the above cited patents disclose a battery charging system including control circuits for completely burning off the charging current to the battery when the voltage, temperature, and/or charging current exceed corresponding maximum values.
Furthermore, none of the above cited references disclose a battery charging system incorporating an electronic current limiting integrated circuit in combination with an automatic signal circuit for sequentially signalling progressively increasing values of the charging current.